1. Field of the Invention
Applicant's invention relates to an electrical apparatus and more particularly to devices normally employed as part of a gaseous discharge lighting system. The invention provides an electronic circuitry for initiating of electrical current through gaseous discharge lamps, sustaining conduction of electrical current through gaseous discharge lamps when such conduction of electrical current would otherwise cease, providing active suppression of electrical transient voltages within the apparatus normally employed with gaseous discharge lamps for their operation, providing active suppression of electrical transient voltages from sources internal and external to the gaseous discharge lighting apparatus, providing significant attenuation to the propagation of undesirable conducted radio frequency interference emissions back into the power line mains supplying power for the operation of gaseous discharge lighting equipment, and providing significant attenuation to radiated radio frequency interference emissions from the gaseous discharge lighting equipment.
2. Background Information
The typical gaseous discharge lamp can experience startup delays due to various problems. It is known that gaseous discharge lamps themselves present particular problems with regard to 1) starting at low ambient temperatures, 2) peculiarities intrinsic to the various types and sizes or power ratings of gaseous discharge lamp construction, 3) extended hot re-strike times if extinguished even very briefly due to external causes, such as loss of supplying power, and internal causes, such as age, during normal operation, and 4) changing their characteristics to beyond that which the associated ballasting apparatus can sustain conduction of electrical current through the particular gaseous discharge lamp. For example, if low pressure sodium lamps go out, the lamp will typically not relight for 20 minutes. This can cause safety and/or security problems depending on the location of the lamp.
Another significant disadvantage to present gaseous discharge lighting systems is high EMI/RFI interference from the lamp itself. It is known that during the operation of gaseous discharge lamps, various nonlinear effects intrinsic to the operation of gaseous discharge lamps commonly and inadvertently couple significant and undesirable radio frequency interference back into the power line mains supplying the power necessary for the operation of the overall gaseous discharge lighting apparatus and equipment as well as radiate significant and undesirable radio frequency interference energy into the environment from the lamps themselves. The standard gaseous discharge lighting system cannot be used in many countries due to strict regulations on electromagnetic noise pollution. A third problem with the existing gaseous discharge lighting systems is that there is no means by which to accurately set the breakover voltage of overvoltage protection devices into the system.
The present invention alleviates the problem of delayed starts by incorporating a self adjusting symmetrical high voltage pulse generator. The self-adjusting symmetrical high voltage pulse generator generates a series of pulses to restart the lamp whenever the lamp goes out or low temperature conditions prevent starting. Presently, it is well-known that a significantly higher than normal operating voltage must be applied to the lamps in order to initiate conduction of an electrical current through the active volume of the lamps. However it is not known in the prior art to apply such high voltage in a series of pulses from a self-adjusting symmetrical high voltage pulse generator.
The symmetry of the generator is also important in the reduction of EMI/RFI interference. The present invention allows the modification of existing gaseous discharge lighting systems for use in other countries that regulate electromagnetic noise pollution. The third benefit of the present invention is the incorporation of a precision electronic crowbar to provide a momentary short to protect the high voltage circuits from transient overvoltages.